/*
 * gleem -- OpenGL Extremely Easy-To-Use Manipulators.
 * Copyright (C) 1998-2003 Kenneth B. Russell (kbrussel@alum.mit.edu)
 *
 * Copying, distribution and use of this software in source and binary
 * forms, with or without modification, is permitted provided that the
 * following conditions are met:
 *
 * Distributions of source code must reproduce the copyright notice,
 * this list of conditions and the following disclaimer in the source
 * code header files; and Distributions of binary code must reproduce
 * the copyright notice, this list of conditions and the following
 * disclaimer in the documentation, Read me file, license file and/or
 * other materials provided with the software distribution.
 *
 * The names of Sun Microsystems, Inc. ("Sun") and/or the copyright
 * holder may not be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED "AS IS," WITHOUT A WARRANTY OF ANY
 * KIND. ALL EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND
 * WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, NON-INTERFERENCE, ACCURACY OF
 * INFORMATIONAL CONTENT OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. THE
 * COPYRIGHT HOLDER, SUN AND SUN'S LICENSORS SHALL NOT BE LIABLE FOR
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 * COPYRIGHT HOLDER, SUN OR SUN'S LICENSORS BE LIABLE FOR ANY LOST
 * REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL,
 * CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND
 * REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF THE USE OF OR
 * INABILITY TO USE THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
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 * DESIGNED, LICENSED OR INTENDED FOR USE IN THE DESIGN, CONSTRUCTION,
 * OPERATION OR MAINTENANCE OF ANY NUCLEAR FACILITY. THE COPYRIGHT
 * HOLDER, SUN AND SUN'S LICENSORS DISCLAIM ANY EXPRESS OR IMPLIED
 * WARRANTY OF FITNESS FOR SUCH USES.
 */

package org.gephi.lib.gleem.linalg;

/**
 * Represents a plane in 3D space.
 */

public class Plane {
    /**
     * Constant for faster projection and intersection
     */
    float c;
    /**
     * Normalized
     */
    private final Vec3f normal;
    private final Vec3f point;

    /**
     * Default constructor initializes normal to (0, 1, 0) and point to
     * (0, 0, 0)
     */
    public Plane() {
        normal = new Vec3f(0, 1, 0);
        point = new Vec3f(0, 0, 0);
        recalc();
    }

    /**
     * Sets all parameters of plane. Plane has normal <b>normal</b> and
     * goes through the point <b>point</b>. Normal does not need to be
     * unit length but must not be the zero vector.
     */
    public Plane(Vec3f normal, Vec3f point) {
        this.normal = new Vec3f(normal);
        this.normal.normalize();
        this.point = new Vec3f(point);
        recalc();
    }

    /**
     * Normal is normalized internally, so <b>normal</b> is not
     * necessarily equal to <code>plane.setNormal(normal);
     * plane.getNormal();</code>
     */
    public Vec3f getNormal() {
        return normal;
    }

    /**
     * Setter does some work to maintain internal caches. Normal does
     * not need to be unit length but must not be the zero vector.
     */
    public void setNormal(Vec3f normal) {
        this.normal.set(normal);
        this.normal.normalize();
        recalc();
    }

    public Vec3f getPoint() {
        return point;
    }

    /**
     * Setter does some work to maintain internal caches
     */
    public void setPoint(Vec3f point) {
        this.point.set(point);
        recalc();
    }

    /**
     * Project a point onto the plane
     */
    public void projectPoint(Vec3f pt,
                             Vec3f projPt) {
        float scale = normal.dot(pt) - c;
        projPt.set(pt.minus(normal.times(normal.dot(point) - c)));
    }

    /**
     * Intersect a ray with the plane. Returns true if intersection occurred, false
     * otherwise. This is a two-sided ray cast.
     */
    public boolean intersectRay(Vec3f rayStart,
                                Vec3f rayDirection,
                                IntersectionPoint intPt) {
        float denom = normal.dot(rayDirection);
        if (denom == 0) {
            return false;
        }
        intPt.setT((c - normal.dot(rayStart)) / denom);
        intPt.setIntersectionPoint(rayStart.plus(rayDirection.times(intPt.getT())));
        return true;
    }

    //----------------------------------------------------------------------
    // Internals only below this point
    //

    private void recalc() {
        c = normal.dot(point);
    }
}
